This section is intended to provide a background to the various embodiments of the technology described in this disclosure. The description in this section may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and/or claims of this disclosure and is not admitted to be prior art by the mere inclusion in this section.
Due to the increasing demand to enhance wireless capacity and due to lack of availability of spectrum in lower frequency range (e.g. 800 MHz-3 GHz), the use of frequencies in 10's of GHz range is being investigated. For the future wireless network, investigations are going on to explore higher frequency bands, for instance, in the range of 30 GHz, 60 GHz and 98 GHz. At this frequency, a very large bandwidth of spectrum is available. This means both operating frequency and bandwidth for the future networks are expected to be much higher than those for legacy wireless networks.
However, due to large signal attenuation with respect to path loss, the network operating over such high frequencies is supposed to cover small areas with densely deployed radio access nodes (ANs). Considering that such dense deployment is particularly useful to provide sufficient coverage for indoor/hot areas, it has been agreed to exploit Ultra-Density Network (UDN), which is also referred to as millimeter Wave-Radio Access Technology (mmW-RAT), for the future wireless system.
Currently, it is supposed that the total carrier bandwidth of the mmW-RAT can be up to 1 or 2 GHz. This bandwidth can be composed by a number of sub-band carriers of a certain bandwidth, e.g. 100 MHz. By way of example, FIG. 1 illustrates one mmW-RAT carrier with 4 sub-bands. The smallest resource grid in the figure is an Atomic Scheduling Unit (ASU), which corresponds to a subband in the frequency domain and to a subframe in the time domain.
To allocate the available resources, a contention based resource allocation scheme and/or a scheduling based resource allocation scheme may be applied.
One example of the contention based resource allocation scheme is the well-known Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, wherein a communication device (e.g., a User Equipment (UE)) shall firstly send a contention message to make a reservation for some resources before occupying them and the resource reservation is successful if it is accepted by a peer communication device (e.g., an AN serving the UE). In such a manner, it can be ensured that resources are dedicatedly occupied by the communication device making the successful reservation. Accordingly, collision between communication devices in resource occupation can be avoided.
In the scheduling based resource allocation scheme, a Central Control Unit (CCU) shared by a cluster of Access Nodes (ANs) is relied on to allocate resources to different radio links. To be specific, the CCU configures, for each of the radio links associated with the ANs, a template frame indicating multiple types of resources allocated to the radio link.
By way of illustration rather than limitation, in a mobile network based on the mmW-RAT, the resources allocated to a radio link may be classified into dedicated resources, on which data transmission can be performed with high reliability, and shared resources, on which data transmission of lower reliability can be performed to achieve enhanced data rate. If a radio link is allocated with dedicated resources, the radio link will have the highest priority to access these resources while any other radio link shall control its interference to the radio link on the allocated dedicated resources. On the other hand, if a radio link is allocated with shared resources, both the radio link and other radio links can access these resources and the use of these resources by one of the radio links may produce interference to the others.
For illustration, an exemplary radio network where the scheduling based resource allocation scheme may be implemented is depicted in FIG. 2. In addition to AN1-AN4, the network comprises a CCU responsible to determine, for radio link 1, a template frame based on relevant measurements and/or data rate requests from peer communication devices (i.e., AN1 and User Equipment 1 (UE1)) on radio link 1. Further, the template frame determined for radio link 1 can be updated by the CCU during a communication session according to various varying factors, such as interference measurements and/or data rate requests from radio link 2 which is a neighboring link of radio link 1. Likewise, the CCU determines a template frame for radio link 2 and updates the template frame by taking into account radio link 1's impact on radio link 2.
Further details of the template frames configured for radio links 1 and 2 are given in FIG. 3. As illustrated, each of the template frames specifies, for its associated radio link whose number is given in the colored ASUs, both dedicated resources (shown as dark-colored ASUs) and shared resources (shown as light-colored ASUs).
Instead of being applied separately, the contention based resource allocation scheme and the scheduling based resource allocation scheme may be applied jointly (for example, in a time division manner) as illustrated in FIG. 4. Accordingly, contention-based resources may be allocated to a radio link, in addition to the dedicated and shared resources. Then, the resources allocated to the radio link may be classified into scheduling-based resources (including both the dedicated and shared resources) and contention-based resources, instead of being classified into dedicated and shared resources.
Referring back to FIG. 3, the scheduling based resource allocation scheme allows certain ASUs to be allocated to radio link 1 as dedicated resources and meanwhile allocated to radio link 2 as shared resources.
To make full use of the time-varying capacity of a radio link, the Link Adaption (LA) technology has been proposed and widely adopted in wireless networks. According to the existing LA approach, a single LA process is run for one radio link to adaptively select, according to measurements and acknowledgement feedbacks associated with the link, Modulation and Coding Schemes (MCS's) for transmissions on the radio link aiming at a desired quality target (such as Block Error Rate (BLER)). As such, the selected Modulation and Coding Scheme (MCS) can be adaptive to the channel fading variation and more importantly the interference variation of the link, and hence the usage efficiency of the resources allocated to the link can be significantly improved.
Due to the fact that the resource allocation scheme in for example the 5G network is much different from that in the legacy wireless networks (particularly, in the 5G network, one radio link may be allocated with different types of resources), simply adopting the existing LA approach in the 5G network may lead to non-optimal link performance.